1. Field of the Invention
This invention relates to an automatic focus adjusting device of a camera or the like.
2. Description of the Prior Art
As a device of this type, there is a distance measuring and automatic focus adjusting device which determines the object distance by using an array of charge accumulating type photoelectric conversion elements comprising charge coupled devices (hereinafter referred to as CCD) disclosed, for example, in U.S. Pat. No. 4,078,171.
Two types of the distance measuring and automatic focus adjusting device using such type of charge accumulating type photoelectric conversion element array are conceivable. A first type is an automatic focus adjusting device in which distance measurement is effected in accordance with the output from the photoelectric conversion element array corresponding to the accumulated charge at a point of time whereat the picture-taking lens of the camera is stopped from moving and on the basis thereof, the picture-taking lens is driven to the determined distance. A second type is a device which uses the output of the charge accumulating type photoelectric conversion element array for distance measurement during both movement and stoppage of the picture-taking lens.
In these two types of systems, the conformity with the conditions of the object to be photographed becomes a problem depending on the length of the quantity-of-light integrating time (charge accumulating time) of the photoelectric conversion element array or of the response time of the picture-taking lens driving system. That is, in the former type, where the brightness of the object is low and the quantity-of-light integrating time is relatively long, accuracy of the picture-taking lens driving and quick response can be expected, but when the brightness of the object becomes high and the quantity-of-light integrating time becomes relatively short, the picture-taking lens driving system becomes sharply responsive to camera vibration (hand vibration) or movement of the object and therefore, the stability of the picture-taking lens driving becomes poorer. On the other hand, in the latter type, when the brightness of the object is high, smooth and stable picture-taking lens driving can be expected for camera vibration or movement of the object, but when the brightness of the object becomes lower, the quantity of light integrating time of the photoelectric conversion element array becomes relatively long and therefore, the responsiveness of the picture-taking lens driving is aggravated (the response becomes slower).